(a) Field of the Invention
The present invention relates to a control apparatus and method of a power transmission system. More particularly, the present invention relates to a control apparatus and method of a power transmission system that use power of an engine and a motor/generator with one planetary gear set and two friction members.
(b) Description of the Related Art
Environmentally-friendly technology for vehicles is a critical technology of the future vehicle industry, and advanced automobile manufacturers have been developed environmentally-friendly vehicles for satisfying environmental rules and improving fuel efficiency. Accordingly, automobile manufacturers have developed an electric vehicle (EV), a hybrid electric vehicle (HEV), and a fuel cell electric vehicle (FCEV) for the future vehicle technology.
There are various technical limitations of the future vehicles such as weight and cost, such that automobile manufacturers are interested in hybrid vehicles as an alternative plan of practical problems for satisfying regulations of exhaust gas and improving fuel efficiency. Hybrid vehicles are vehicles that use two or more energy sources (e.g., power sources) and may be implemented in various types, in which, generally, a gasoline engine or a diesel engine which generally uses a fossil fuel as the power source in the related art and a motor/generator driven by electrical energy are combined.
In particular, the hybrid vehicles use a motor/generator with relatively high low-speed torque characteristics as a main power source at a low speed, and use an engine with relatively high high-speed torque characteristics as the main power source at a high speed. Accordingly, the hybrid vehicles stop the engine using fossil fuel and use the motor generator in a low speed range, to advantageously improve fuel efficiency and reducing exhaust gas.
The power transmission systems of the hybrid vehicles are different in durability, power transmission efficiency, and size in accordance with connection configurations, such that research for achieving a compact power transmission system with a minimal loss of power has been conducted. Further, research regarding efficient control methods of the power transmission system has been conducted.
The above information disclosed in this section is merely for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.